1. Field of the Invention
The present invention relates to a printing apparatus, a printing apparatus control method, and a storage medium.
2. Description of the Related Art
Conventionally, when a copying machine and a multifunctional image forming apparatus read an image, background color removal processing has been employed as a technique for preventing so-called offset reproduced on a front side by an image that is on the back side of a document. In background color removal, a user performs gradation correction on read image information according to a level for decreasing an image reproduction density that is specified from an operation screen or according to a background color level estimated from a histogram of the luminance or density level of the read image information. Since the quality of the read image can deteriorate depending on this level, especially with respect to a background color level, techniques for increasing the estimation accuracy of the background color level have been proposed (Japanese Patent Application Laid-Open Nos. 5-183749 and 8-237485).
However, since the characteristics of the histogram differ depending on various factors, such as the type of image printed on the document, the paper thickness of the document, and the irradiation intensity of the light source, an estimation error will necessarily occur.
Further, rather than estimating the background color level from a histogram, the optimum background color level can also be determined by reading a document printed on only a back side, and using a result obtained by reading only the image that is actually offset, as discussed in Japanese Patent Application Laid-Open No. 2001-91621.
However, in a conventional image forming apparatus, the document conveyance system of a document conveyance type image reading unit and the printing sheet conveyance system of the unit that prints an image onto a printing sheet are configured independent of each other. Consequently, a troublesome user operation is required. More specifically, the background color level is determined by reading in advance a document printed on only one side (pre-scanning). Then, printing is performed on the other side, and then again the document printed on both sides needs to be read.